Storm Sewers

CI1550 Hydraulics and Hydrology: The Water Resource
Tools Available in Autodesk® Infrastructure Design Suite
Dino Lustri, P.E., P.S., ACI
Consulting Civil Engineer, Surveyor and Mapper
Water Resources
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Class summary
 Autodesk has given us a variety of water resource tools in Autodesk
Infrastructure Design Suite. If you are a manager or a designer, you need
to know if you can stop paying maintenance on competing software and
move your organization forward with a single suite of tools. You want to
know what is in the suite from someone who does what you do and if it
can do the things you need it to do. In this class, you get a better
understanding of what equations are being used in which applications
and how to find the right fit for the project requirements that are being
passed on down to you. We review Storm Sewers, Hydrographs,
Express Tools, SSA, and River Analysis. You also learn some tips and
tricks that those who already are familiar with these tools can use.
Goal: Familiarize you with the five hydraulics and
hydrology tools included in the Autodesk
Infrastructure Suites.
Key learning objectives
At the end of this class, you will be able to:
Describe which H&H tools are available to you in the suites.
Determine which H&H tool will best suit the requirements being asked of you.
Decide if you can terminate competitive H&H products and save money.
Use some tips and tricks for general H&H efforts.
Express Tools
Uses Bernoulli's energy equation Standard Step method when computing the hydraulic profile for
outlet control.
It uses Manning's equation to determine head losses due to pipe friction.
Hydraflow Express Extension uses the following equation:
Uses Manning’s equation to compute Qs at varying depths of flow. When a known Q is specified, it
solves for the depth using an iterative procedure.
Follows the basic methodology of FHWA HEC-22 for inlet interception capacity calculations.
Clogging factors are not used in this program.
Curb inlet
Curb inlet
Grate inlet
Grate inlet
Slotted inlet
Slotted inlet
Q < 5.5 cfs, Slope < 0.09
Uses the Unit Hydrograph Method for calculating runoff hydrographs. More specifically, it uses the
triangular D-hour Unit Hydrograph approach.
Uses a variety of forms of the fundamental weir equation to compute flow rates at varying depths of
flow. Sources for these equations include HEC-22 and "Open Channel Hydraulics", Richard French.
Uses fixed values for the design velocity, min. and max. pipe sizes, min. slope, and so on.
You can modify these values by editing Express.ini located in…
C:\Users\dlustri\AppData\Local\Autodesk\C3D 2014\enu\HHApps\Express
Uses the HEC-22, NRCS, and the Rational methods for most hydrologic calculations.
NEH-4: Hydrology; Section 4, National Engineering Handbook
TR-20: Computer Program Manual, 1992
TR-55: Urban Hydrology For Small Watersheds
A Guide To Hydrologic Analysis Using SCS Methods, Richard McCuen
HEC No. 12: FHA, Drainage of Highway Pavements
HEC No. 22: FHA, Urban Drainage Design Manual
Hydrology for Engineers; Linsley, Kohler & Paulhus
Urban Storm Drainage Management; Sheaffer, Wright, Taggart & Wright
Handbook of Hydraulics; Brater, King, Lindell, Wei
Uses the unit hydrograph method for calculating runoff hydrographs. It uses the triangular D-hour
unit hydrograph approach as used in TR-20. The unit hydrograph represents a 1-inch rainfall over
one time interval.
Mountainous (600) > 484 > Swampy (300)
Storm Sewers
Storm Sewers
Uses the Bernoulli Energy-based Standard Step method to compute the hydraulic profile.
It uses Manning's Equation to determine head losses due to pipe friction.
Storm Sewers
It uses Manning's Equation to determine head losses due to pipe friction.
- Calculates pipes flowing full
- (S) Slope of the invert refers to Energy Line Slope
When the real velocity is different from the assumed velocity, the computed Tc is incorrect and thus the computed Q
and resulting HGL are incorrect. The EMS solves this problem by re-computing the HGL based on actual flow rates
and actual Tc. To do this Hydraflow Storm Sewers Extension must compute three system iterations so that the
computed Tc match those that were assumed with reasonable accuracy.
Hydraflow Storm Sewers Extension first computes the HGL using Tc based on the design velocity. It then computes
the system a second time using Tc based on actual velocities. These new velocities are still incorrect because they
are based on the original HGL calculation, however they are more accurate than those used on the first trial. As one
would expect, several system iterations would cause the Q, Tc, and resulting HGL to converge to correct values. After
extensive testing, it has been concluded that three iterations is the most practical balance between accuracy and
time required to produce the results.
SSA: Storm and Sanitary Analysis
Storm and Sanitary Analysis
Hydrology Modeling Capabilities
USEPA SWMM 5.0 (also imports and exports XPSWMM models)
US Army Corps HEC-1
Rational Method
Modified Rational Method
UK Modified Rational (Wallingford Procedure)
DeKalb Rational Method
Santa Barbara Unit Hydrograph
Delmarva Unit Hydrograph
Long-Term Continuous Simulation
Maricopa & Pima Counties (Arizona) Papadakis-Kazan methodology
Harris County (Texas) Method
Storm and Sanitary Analysis
Hydraulic Modeling Capabilities
1) Kinematic Wave (default)
2) Steady Flow
3) Hydrodynamic (i.e., Saint Venant equations)
Storm sewers, sanitary sewers, and combined sewers
Open channels
Bridges and culverts
Curb and gutter storm drain inlets
Detention ponds and outlet structures
Force mains (using either Hazen-Williams or Darcy-Weisbach equations)
Flood overflow routing
Storm and Sanitary Analysis
Kinematic Wave & Steady Flow
Cannot model backwater. Similar to Storm Sewers. HGL Spikes.
Can model…
- backwater effects
- flow reversal
- surcharging
- looped connections
- pressure flow
- tidal outfalls
- interconnected ponds
Storm and Sanitary Analysis
In SSA, the equations used are…
For open channel and partially filled conduit, Mannings.
For Steady Flow and Kinematic Wave, the slope is the pipe slope.
For Hydrodynamic, it is the friction slope.
For pressurized systems, Hazen-Williams or Darcy-Weisbach replace Mannings.
SSA vs. Storm Sewers vs. Hydrographs
So why use the other packages? Why don’t we only use SSA?
1) Overkill
2) Time to enter data
3) Interactive peak flow design is better in Hydrographs and Storm Sewers
It depends on what you are being asked to do.
River Analysis
River Analysis
HEC-RAS with benefits
- Takes advantage of all your terrain tools in Civil 3D.
- Extract large amounts of data, rapidly,
- Taking advantage of your Civil 3D dynamic environment.
Let’s take a brief look at the suite…
What software can you replace?
Which Suites have which tools?
MAP has the maintenance work space to facilitate the gathering of data.
Civil 3D Water Resource CAD tools:
Stage Storage
Water Drop
Watershed Style
Undocumented Commands…
Find your comfort level…calibrate….compare….verify
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